The present invention relates generally to the preparation of ethylenediamine dinitrate, and more particularly to a method for the safe and economical preparation of ethylenediamine dinitrate in an organic medium without the use of concentrated nitric acid and using water-insoluble amines as a vehicle for achieving the dissolution of the starting materials.
Ethylenediamine dinitrate is a chemical explosive which finds use as a component in pressed mixtures for shells and as a component in castable eutectic mixtures with ammonium nitrate and other compounds for bomb fills. It is currently prepared according to a process described in "Explosive Performance Modification by Cosolidification of Ammonium Nitrate with Fuels," by I. Akst and J. Hershkowitz, Technical Report 4987 from the Picatinny Arsenal, Dover, N.J. (1976). Therein the authors teach the preparation of ethylenediamine dinitrate in batches of 50 to 500 grams by acidifying a cooled solution of ethylenediamine, water and ethanol with concentrated nitric acid, stirring for some period of time, filtering the precipitated ethylenediamine dinitrate product, and washing and drying the precipitate. This method is inefficient, because of the necessity of the use of concentrated nitric acid for the reaction.
The use of high-molecular-weight, water-insoluble amines as vehicles for rendering ionic organic compounds soluble in organic solvents is well-known. In "Production of the Ammonium Salt of 3,5-dinitro-1,2,4-triazole by Solvent Extraction," U.S. Pat. No. 4,236,014 issued to Kien-yin Lee and Donald G. Ott on Nov. 25, 1980, the inventors describe the use of a high-molecular-weight, water-insoluble amine to extract a large organic acid starting material from aqueous solution into solution with an organic solvent, from where a chemical reaction is made to occur with other compounds producing thereby an ionic organic product which is insoluble in the organic solvent. The method of the subject invention, however, includes the extraction of an inorganic acid from aqueous solution using a high-molecular-weight, water-insoluble amine, rendering it soluble in an organic solvent thereby, from which the chemical reaction which leads to the desired insoluble ethylenediamine dinitrate product can be performed safely and efficiently. Of significant unobvious nature in this type of extraction is whether the amine extracting agent will be released by the base used as one of the principal reactants in the desired synthesis. That is, it is desirable that the amine be released in its original form after the addition reaction of the organic base which leads to the production of the desired product. It is not possible to predict whether ethylenediamine is basic enough to displace the amine in the acid nitrate salt of the amine extracting agent, which replacement is essential to the success of the subject invention.